Volvo Penta 5.0 GLE Overheat

[Offshur]

2004 5.0 GLE started overheating this year (mid-summer) at high (2500-3000) rpm's. I have clear hoses on the engine with no bubbles, replaced the raw water pump and the circulating pump. The heads have been off and are clear, as are the intake and exhaust manifolds and risers. The "y" pipe on this model has no flappers and is clear. The power steering exchanger is clear. I pulled the lower unit, everything is clear and tight. The thermostat has been checked and opens properly. The prior raw water impeller has been changed every year and never lost any blades. The temperature sending unit has been changed. An alternate overheat sending unit has been installed with no change of results. Scanning the engine with a IR temperature gauge shows the block, risers, manifolds, hoses at "normal" temperatures except for the front "half" of the thermostat housing where the overheat sending unit is located. That is reading ~200 deg. It's at the boatyard now They ran it with muffs and said it had good water flow. They are as lost as I. I'm really hoping for some divine words of wisdom to solve this and get me back on the lake.

 

[ericga]

Any chance hoses are connected wrong or kinked somehow? Is the impeller OEM? Never seen it myself but some people here experienced an high rpm overheating condition with aftermarket impellers (blades being thinner I believe).

 

[tlewis1]

There is a rubber grommet on the water tube in between the drive halfs that could be causing issues or the o-ring/seal on the back of the water hose at the gimbal housing.

You'll have to remove the drive and split the upper and lower to access the grommet and while the drive is off you will be able to remove the intake hose from the gimbal and replace the o-ring.

 

[Scott Danforth]

circulating pump

 

[Offshur]

All the hoses are correct and clear, the lower unit was removed and the hose was checked and the o-rings were installed with care to assure they were properly in place during bolt up. There are no indications of air in the clear hose sections. The raw water pump is a new unit with a new stock impeller. The circulation pump is new. I stopped at he boat yard yesterday and the mechanic said he ran it on muffs and it did not overheat. He is going to splash it today, weather permitting, to see how it does under load. I'll send a follow up with the results. In the mean time, all suggestions are gratefully accepted.

 

[bajaunderground]

any chance the gauge has gone bad? Are you getting alarms along with temps?

 

[Offshur]

Talked to the mechanic at the boatyard. They splashed the boat and found that it overheats under load, never on the muffs. The block is getting hot and he suspects that the water flow is insufficient. It has a new raw water/impeller pump and circulating pump and the belt is not slipping. Something must be blocking flow through the block. It has never had an impeller failure and has always been in freshwater. When the manifolds, intake, and heads were off they appeared clear with only a rust color showing, no rust scale was found.